SLC504 pulling data from Controllogix using 1747-AENTR?

I'm looking for a cheap way to pull data from a controllogix system to a SLC504 so that I can use the DH+ connecting on the 504 which is connected to a historian system (along with 15 other 504's). I know that a 1747-AENTR can be used to replace the processor of a 504 but can it be used to read/msg from a controllogix to a 504 processor? I know that an AN-X2-AB-DHRIO can be used to read DH+ through Ethernet connection but it can't be used to read Ethernet through DH+ connection or I would use it. Rather than installing or changing a machine over to compactlogix from controllogix, I'd rather just try to read the data. Even if I have to msg from a controllogix to a data file in the 504 and then read that through the DH+ connection to my historian system. Any suggestions?

Use the DF1 port

1756-DHRIO cost as low as $100 on ebay.

DHRIO in the Logix would be the quickest way. But the best way would be to get your historian on Ethernet and upgrade the SLC to 5/05 or use the AENTR and migrate the program to the Logix. DH+ is going away fast. I don't know how your historian is getting on DH+, but if it's an old ISA card that could be a real problem if it goes bad. You can still get that stuff on eBay, but I wouldn't want my data to be counting on eBay parts. Best to bite the bullet and upgrade..